Bluetooth® is a low-power, short-range wireless networking standard designed for local area voice and data communication systems. The devices operating in these systems typically form an ad hoc wireless network when within communication range of one another. One communication device assumes the role of master and temporarily manages and synchronizes the other communication devices as slaves within the ad hoc wireless network. Portable battery operated devices, such as portable radios, are well suited for Bluetooth applications.
There is a growing interest, particularly in the public safety arena, in wireless Personal Area Networking (PAN) accessories to simplify communications, enhance safety, and increase effectiveness. Bluetooth is a PAN system designed for both digital toll quality voice and data traffic with a maximum channel data capacity of about 700 kb/s. Bluetooth data is coded in packets so that errors are detected and packets are retransmitted until correctly received. Short of a permanent loss of the communications link, the correct data will eventually be delivered. In the face of interference, data throughput will be degraded, but the correct data will eventually get through. Thus, Bluetooth is regarded as having “reliable data transfer” capability. Unfortunately, Bluetooth is not considered to have “reliable audio transfer” capability. Missed packets are considered better to be lost (as a noise or a pop) rather than delayed because delays would pose an equal or worse audio defect. Instead, Bluetooth audio was designed with variable bit error correction coding to protect the audio bits.
As the Bluetooth framework becomes incorporated into portable radio and mobile environments, there are concerns that the Bluetooth audio modes may not be robust enough to provide acceptable audio quality. Additionally, the Bluetooth system includes encrypted modes that provide a more secure audio link. While not generally in use today, there are plans for use of the encrypted modes in future mobile environments. These encrypted modes are likely to cause even further audio degradation.
Accordingly, it would be desirable to have a means of enhancing audio intelligibility within the Bluetooth standard. Such enhancements would improve the reliability, sensitivity, and quality of the audio links of portable communication devices operating within the Bluetooth standard.